A method of membrane separation of associated petroleum gas is known using capillary condensation approaches described in the patent EP2539043 and disclosing a method of separating natural gas on zeolite membranes by means of condensation of heavier hydrocarbons in microporous membrane layer, on different sides of which a pressure drop is provided. This method allows for separating a hydrocarbon mixture without cooling the membrane or feed gas. In accordance with this method the starting mixture is fed at a pressure of more than 5 bars whereas the permeate side pressure is 4 to 10 bar lower. This leads to condensation of heavier hydrocarbons in membrane pores whereas selectivity is determined by the size of these pores. For plants of such type mostly mesoporous zeolite membranes are used, namely those based on ZSM-5 (NanAlnSi96-nO192.16H2O, 0<n<27).
A significant disadvantage of the technique described above is low permeability of the membrane (less than 1 m3/m2·atm·h) which makes this method ineffective and uneconomical at treatment of industrial gases. Low permeability of these membranes is determined by small diameter of zeolite pores, which, on the one hand, allows for carrying out condensation of heavy hydrocarbons without cooling the membrane, while, on the other hand, significantly reduces membrane permeability. This solution has been selected as a closest prior art (prototype) for the claimed method of membrane separation of hydrocarbons.
A significant increase in membrane permeability while maintaining the gas transfer mode through the membrane according to capillary condensation and flow mechanism can be achieved by increasing the diameter of membrane pores at insignificant cooling thereof.